In recent years, there has been global interest in meeting targets relating to energy affordability and security while taking into account greenhouse gas emissions. This has heightened major interest in potential inve...In recent years, there has been global interest in meeting targets relating to energy affordability and security while taking into account greenhouse gas emissions. This has heightened major interest in potential investigations into the use of supercritical carbon dioxide (sCO2) power cycles. Climate change mitigation is the ultimate driver for this increased interest;other relevant issues include the potential for high cycle efficiency and a circular economy. In this study, a 25 MWe recompression closed Brayton cycle (RCBC) has been assessed, and sCO2 has been proposed as the working fluid for the power plant. The methodology used in this research work comprises thermodynamic and techno-economic analysis for the prospective commercialization of this sCO2 power cycle. An evaluated estimation of capital expenditure, operational expenditure, and cost of electricity has been considered in this study. The ASPEN Plus simulation results have been compared with theoretical and mathematical calculations to assess the performance of the compressors, turbine, and heat exchangers. The results thus reveal that the cycle efficiency for this prospective sCO2 recompression closed Brayton cycle increases (39% - 53.6%) as the temperature progressively increases from 550˚C to 900˚C. Data from the Aspen simulation model was used to aid the cost function calculations to estimate the total capital investment cost of the plant. Also, the techno-economic results have shown less cost for purchasing equipment due to fewer components being required for the cycle configuration as compared to the conventional steam power plant.展开更多
The process based on supercritical fluid extraction for reprocessing of the spent nuclear fuel has some remarkable advantages over the plutonium-uranium extraction(PUREX) process.Especially,it can minimize the generat...The process based on supercritical fluid extraction for reprocessing of the spent nuclear fuel has some remarkable advantages over the plutonium-uranium extraction(PUREX) process.Especially,it can minimize the generation of secondary waste.Dynamic reactive extraction of neodymium oxide(Nd2O3) in supercritical carbon dioxide(SC-CO2) containing tri-n-butyl phosphate-nitric acid(TBP-HNO3) complex was investigated.Temperature showed a positive effect on the extraction efficiency,while pressure showed a negative effect when the unsaturated TBP-HNO3 complex was employed for the dynamic reactive extraction of Nd2O3 in SC-CO2.Both temperature and pressure effects indicated that the kinetic process of the reactive extraction was controlled by the chemical reaction.A kinetic model was proposed to describe the extraction process.展开更多
A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The ...A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The compound with electron-withdrawing substituent on benzene ring had even better solubility than the compounds with electron-donating substituent.展开更多
1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and indu...1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry.展开更多
The use of supercritical fluid carbon dioxide (SFCO2) in extraction of lanolin and its alcohol is superior to the conventional solvent extraction method. Its distinctive advantages include high extractive ratio, nonto...The use of supercritical fluid carbon dioxide (SFCO2) in extraction of lanolin and its alcohol is superior to the conventional solvent extraction method. Its distinctive advantages include high extractive ratio, nontoxic and nonflammable solvents, and minimal by -product pollution. The resulting refined lanolin and its alcohol have light color and little odor, and can be used as raw materials for high grade cosmetic products.展开更多
Separation of molybdenum isotope complexes by supercritical fluid extraction (SFE) with carbon dioxide was studied experimentally. The extraction of molybdenum isotope complexes was carried out in the updated extracti...Separation of molybdenum isotope complexes by supercritical fluid extraction (SFE) with carbon dioxide was studied experimentally. The extraction of molybdenum isotope complexes was carried out in the updated extraction chamber (reactor) of the SFE-U installation, which provided an initial pressure of P ≤ 20 MPa at constant temperatures of the upper T1 = 35°C and bottom T2 = 45°C flanges. The device, through which the eluent was discharged, involved a set of four thin tubes of different lengths located inside the reactor. The axes of the tubes and the reactor are parallel and the tubes are equally spaced circumferentially inside the reactor. The extract was removed from each tube through channels isolated from each other and located in the bottom flange with cylindrical expansion, in which several layers of filter paper were placed. After passing through the filters the extract entered a restrictor designed to remove the eluent from the reactor. The initial pressure of carbon dioxide and the holding time of the extract were specified in the experiments. The level of the eluent sampling was set by the lengths of the tubes depending on the reactor height. A method of producing molybdenum complexes was described. It was experimentally shown that at an initial pressure of 20 MPa and a given holding time a difference from the natural content of Mo isotopes for given heights of extract sampling depending on the reactor height was observed in extracts removed through filters. The ranges of deviation of the content of molybdenum isotopes in extracts from natural one were determined.展开更多
The monomer fraction density based analysis of precise thermophysical data for pure fluids is developed to study the molecular structures in supercritical fluids in general and in CO2 in particular. The series expansi...The monomer fraction density based analysis of precise thermophysical data for pure fluids is developed to study the molecular structures in supercritical fluids in general and in CO2 in particular. The series expansion by powers of the monomer fraction density of the potential energy density is used to discover the cluster structure in supercritical fluids and the clusters’ bond energies in CO2. The method of clusters separation between classes of loose and dense clusters in the CO2 supercritical fluid is developed. The method of the energetically averaged number of dense clusters is developed to study the mechanism of the soft structural transition between the gas-like and liquid-like fluids in the supercritical CO2.展开更多
Aspen Adsim was used to simulate the fractionation of citrus oil with extraction and adsorption combined method in supercritical carbon dioxide.The dynamic behavior in a isothemal and adiabatic bed could be described ...Aspen Adsim was used to simulate the fractionation of citrus oil with extraction and adsorption combined method in supercritical carbon dioxide.The dynamic behavior in a isothemal and adiabatic bed could be described succesfully,and the simulation results agreed with the experimental data.The effect of adsorption time,the flow rate of feed on the concentration of components in product and the recovery were studied.The amount of loading composition on the adsorbents changed with adsorption time and axial distance of bed was also investigated.展开更多
A new expression of mixing rule is suggested according to the Mayson′s mixing rule in this paper, which adopts the Redlich Kwong cubic equation of state and the modified Chueh Prausnitz method to calculate the expe...A new expression of mixing rule is suggested according to the Mayson′s mixing rule in this paper, which adopts the Redlich Kwong cubic equation of state and the modified Chueh Prausnitz method to calculate the experiment critical points of six binary mixtures CO 2+toluene, CO 2+cyclohexane, CO 2+ n butanal, CO 2+ i butanal , CO 2+methanol, CO 2+ethanol. The coefficients of interaction parameter in the expression of mixing rule were optimized from experimental data. The calculated results of critical temperature and critical pressure meet the experiment data well. The maximum relative errors of temperature and pressure between the calculation results and experiment data are 1 493% and 5 2236% respectively, indicating that the proposed expression of mixing rule is reasonable. This may provide a fundamental method for studying and predicting the properties of supercritical fluids.展开更多
Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the re...Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.展开更多
Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate （DMC） from methanol and carbon dioxide （quaternary mixture of carbon dioxide ＋ methanol ＋ water ＋ DMC） were mea...Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate （DMC） from methanol and carbon dioxide （quaternary mixture of carbon dioxide ＋ methanol ＋ water ＋ DMC） were measured using a high-pressure view cell. The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition （initial ratio of carbon dioxide to methanol）. Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.展开更多
Morphology of hydraulic fracture surface has significant effects on oil and gas flow,proppant migration and fracture closure,which plays an important role in oil and gas fracturing stimulation.In this paper,we analyze...Morphology of hydraulic fracture surface has significant effects on oil and gas flow,proppant migration and fracture closure,which plays an important role in oil and gas fracturing stimulation.In this paper,we analyzed the fracture surface characteristics induced by supercritical carbon dioxide(SC-CO_(2))and water in open-hole and perforation completion conditions under triaxial stresses.A simple calculation method was proposed to quantitatively analyze the fracture surface area and roughness in macro-level based on three-dimensional(3D)scanning data.In micro-level,scanning electron micrograph(SEM)was used to analyze the features of fracture surface.The results showed that the surface area of the induced fracture increases with perforation angle for both SC-CO_(2)and water fracturing,and the surface area of SC-CO_(2)-induced fracture is 6.49%e58.57%larger than that of water-induced fracture.The fractal dimension and surface roughness of water-induced fractures increase with the increase in perforation angle,while those of SC-CO_(2)-induced fractures decrease with the increasing perforation angle.A considerable number of microcracks and particle peeling pits can be observed on SC-CO_(2)-induced fracture surface while there are more flat particle surfaces in water-induced fracture surface through SEM images,indicating that fractures tend to propagate along the boundary of the particle for SC-CO_(2)fracturing while water-induced fractures prefer to cut through particles.These findings are of great significance for analyzing fracture mechanism and evaluating fracturing stimulation performance.展开更多
The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorpti...The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorption in polymers,a displacement and association mechanismon supercritical fluid extraction of the monomer from the polymer is proposed.And,a novel math-ematical model for correlating the solubility data obtained from the experiments is also proposed inthe paper.展开更多
The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and s...The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.展开更多
文摘In recent years, there has been global interest in meeting targets relating to energy affordability and security while taking into account greenhouse gas emissions. This has heightened major interest in potential investigations into the use of supercritical carbon dioxide (sCO2) power cycles. Climate change mitigation is the ultimate driver for this increased interest;other relevant issues include the potential for high cycle efficiency and a circular economy. In this study, a 25 MWe recompression closed Brayton cycle (RCBC) has been assessed, and sCO2 has been proposed as the working fluid for the power plant. The methodology used in this research work comprises thermodynamic and techno-economic analysis for the prospective commercialization of this sCO2 power cycle. An evaluated estimation of capital expenditure, operational expenditure, and cost of electricity has been considered in this study. The ASPEN Plus simulation results have been compared with theoretical and mathematical calculations to assess the performance of the compressors, turbine, and heat exchangers. The results thus reveal that the cycle efficiency for this prospective sCO2 recompression closed Brayton cycle increases (39% - 53.6%) as the temperature progressively increases from 550˚C to 900˚C. Data from the Aspen simulation model was used to aid the cost function calculations to estimate the total capital investment cost of the plant. Also, the techno-economic results have shown less cost for purchasing equipment due to fewer components being required for the cycle configuration as compared to the conventional steam power plant.
基金Supported by the National Natural Science Foundation of China （20506014）.
文摘The process based on supercritical fluid extraction for reprocessing of the spent nuclear fuel has some remarkable advantages over the plutonium-uranium extraction(PUREX) process.Especially,it can minimize the generation of secondary waste.Dynamic reactive extraction of neodymium oxide(Nd2O3) in supercritical carbon dioxide(SC-CO2) containing tri-n-butyl phosphate-nitric acid(TBP-HNO3) complex was investigated.Temperature showed a positive effect on the extraction efficiency,while pressure showed a negative effect when the unsaturated TBP-HNO3 complex was employed for the dynamic reactive extraction of Nd2O3 in SC-CO2.Both temperature and pressure effects indicated that the kinetic process of the reactive extraction was controlled by the chemical reaction.A kinetic model was proposed to describe the extraction process.
文摘A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The compound with electron-withdrawing substituent on benzene ring had even better solubility than the compounds with electron-donating substituent.
基金the National Natural Science Foundation of China(Nos.20332030,20572027,20625205 and 20772034)Natural Science Foundation of Guangdong Province,China(No.07118070).
文摘1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry.
基金Science Foundation of National Education Commission(99053)
文摘The use of supercritical fluid carbon dioxide (SFCO2) in extraction of lanolin and its alcohol is superior to the conventional solvent extraction method. Its distinctive advantages include high extractive ratio, nontoxic and nonflammable solvents, and minimal by -product pollution. The resulting refined lanolin and its alcohol have light color and little odor, and can be used as raw materials for high grade cosmetic products.
文摘Separation of molybdenum isotope complexes by supercritical fluid extraction (SFE) with carbon dioxide was studied experimentally. The extraction of molybdenum isotope complexes was carried out in the updated extraction chamber (reactor) of the SFE-U installation, which provided an initial pressure of P ≤ 20 MPa at constant temperatures of the upper T1 = 35°C and bottom T2 = 45°C flanges. The device, through which the eluent was discharged, involved a set of four thin tubes of different lengths located inside the reactor. The axes of the tubes and the reactor are parallel and the tubes are equally spaced circumferentially inside the reactor. The extract was removed from each tube through channels isolated from each other and located in the bottom flange with cylindrical expansion, in which several layers of filter paper were placed. After passing through the filters the extract entered a restrictor designed to remove the eluent from the reactor. The initial pressure of carbon dioxide and the holding time of the extract were specified in the experiments. The level of the eluent sampling was set by the lengths of the tubes depending on the reactor height. A method of producing molybdenum complexes was described. It was experimentally shown that at an initial pressure of 20 MPa and a given holding time a difference from the natural content of Mo isotopes for given heights of extract sampling depending on the reactor height was observed in extracts removed through filters. The ranges of deviation of the content of molybdenum isotopes in extracts from natural one were determined.
文摘The monomer fraction density based analysis of precise thermophysical data for pure fluids is developed to study the molecular structures in supercritical fluids in general and in CO2 in particular. The series expansion by powers of the monomer fraction density of the potential energy density is used to discover the cluster structure in supercritical fluids and the clusters’ bond energies in CO2. The method of clusters separation between classes of loose and dense clusters in the CO2 supercritical fluid is developed. The method of the energetically averaged number of dense clusters is developed to study the mechanism of the soft structural transition between the gas-like and liquid-like fluids in the supercritical CO2.
文摘Aspen Adsim was used to simulate the fractionation of citrus oil with extraction and adsorption combined method in supercritical carbon dioxide.The dynamic behavior in a isothemal and adiabatic bed could be described succesfully,and the simulation results agreed with the experimental data.The effect of adsorption time,the flow rate of feed on the concentration of components in product and the recovery were studied.The amount of loading composition on the adsorbents changed with adsorption time and axial distance of bed was also investigated.
基金Supported by the National Natural Science Foundation of China(No.2 0 0 76 0 0 4 ) and the Research Fund for the Doctor-al Pragram of Higher Education(No.2 0 0 0 0 0 10 0 5 )
文摘A new expression of mixing rule is suggested according to the Mayson′s mixing rule in this paper, which adopts the Redlich Kwong cubic equation of state and the modified Chueh Prausnitz method to calculate the experiment critical points of six binary mixtures CO 2+toluene, CO 2+cyclohexane, CO 2+ n butanal, CO 2+ i butanal , CO 2+methanol, CO 2+ethanol. The coefficients of interaction parameter in the expression of mixing rule were optimized from experimental data. The calculated results of critical temperature and critical pressure meet the experiment data well. The maximum relative errors of temperature and pressure between the calculation results and experiment data are 1 493% and 5 2236% respectively, indicating that the proposed expression of mixing rule is reasonable. This may provide a fundamental method for studying and predicting the properties of supercritical fluids.
基金The Natural Science Foundation of Jiangsu Province(No.BK20130602)the Applied Basic Research Program of Suzhou(No.SYG201836)the Project of the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.
基金financial support of the State Key Fundamental Research Project(2006CB202504)the National Natural Science Foundation of China(No.20473110)Natural Science Foundation of Shanxi Province.
文摘Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate （DMC） from methanol and carbon dioxide （quaternary mixture of carbon dioxide ＋ methanol ＋ water ＋ DMC） were measured using a high-pressure view cell. The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition （initial ratio of carbon dioxide to methanol）. Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.
基金National Natural Science Foundation of China(Grant No.51804318)the China Postdoctoral Science Foundation Founded Project(Grant No.2019M650963)National Key Basic Research and Development Program of China(Grant No.2014CB239203).
文摘Morphology of hydraulic fracture surface has significant effects on oil and gas flow,proppant migration and fracture closure,which plays an important role in oil and gas fracturing stimulation.In this paper,we analyzed the fracture surface characteristics induced by supercritical carbon dioxide(SC-CO_(2))and water in open-hole and perforation completion conditions under triaxial stresses.A simple calculation method was proposed to quantitatively analyze the fracture surface area and roughness in macro-level based on three-dimensional(3D)scanning data.In micro-level,scanning electron micrograph(SEM)was used to analyze the features of fracture surface.The results showed that the surface area of the induced fracture increases with perforation angle for both SC-CO_(2)and water fracturing,and the surface area of SC-CO_(2)-induced fracture is 6.49%e58.57%larger than that of water-induced fracture.The fractal dimension and surface roughness of water-induced fractures increase with the increase in perforation angle,while those of SC-CO_(2)-induced fractures decrease with the increasing perforation angle.A considerable number of microcracks and particle peeling pits can be observed on SC-CO_(2)-induced fracture surface while there are more flat particle surfaces in water-induced fracture surface through SEM images,indicating that fractures tend to propagate along the boundary of the particle for SC-CO_(2)fracturing while water-induced fractures prefer to cut through particles.These findings are of great significance for analyzing fracture mechanism and evaluating fracturing stimulation performance.
基金Supported by the National Natural Science Foundation of China.
文摘The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorption in polymers,a displacement and association mechanismon supercritical fluid extraction of the monomer from the polymer is proposed.And,a novel math-ematical model for correlating the solubility data obtained from the experiments is also proposed inthe paper.
文摘The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.
